A vast archive of raw census micro data covering Latin America in the period since 1960 survives in machine readable form. The bulk of these data, however, remains inaccessible to researchers. This proposal seeks funding to create harmonized and documented samples of approximately fifty-five Latin American and Caribbean censuses. These micro data and metadata will be made available for scholarly and educational research through a web-based data dissemination system. This project leverages previous federal investments in social science infrastructure. Grants from the National Institutes of Health and the National Science Foundation have laid the groundwork for the Latin American data series by funding many of the initial costs. These projects have underwritten the development of data cleaning and sampling procedures, data conversion and dissemination software, and design protocols for data and documentation. Raw micro data files, internal documentation, and redistribution agreements for the censuses of virtually every Latin American country have been obtained. As a result, the costs of developing new public-use samples for Latin America will be less than half as great as for previous projects. The following tasks must be carried out to capitalize on these past investments and make the Latin American data widely available to researchers: clean raw data files; draw new samples from 100% internal census files; impose confidentiality protections; recode variables into existing harmonized coding systems and develop new coding designs optimized for Latin America; allocate missing and inconsistent data values; create a set of consistent constructed variables; develop harmonized English-language documentation; convert all documentation to the Data Documentation Initiative metadata standard; and improve and maintain the web-based data access system. With over 100 million records covering a forty-year period, the new database will allow social scientists to make comparisons across Latin American nations during four decades of dramatic change. The data series will result in a substantial body of new scientific and policy-relevant health-related research on economic development, demographic transition and population aging, international migration, and many other topics.